Formation of Hydrocarbons from Hydrogenated Graphene in Circumstellar Clouds

TL;DR

This paper proposes a theoretical mechanism explaining how hydrocarbons form from hydrogenated graphene in space, involving bond weakening due to hydrogen and vibrations, supported by DFT simulations.

Contribution

It introduces a new theoretical model for hydrocarbon formation in stellar environments based on density functional theory calculations.

Findings

Hydrogenation weakens C-C bonds in graphene.

Thermal fluctuations can overcome kinetic barriers for hydrocarbon formation.

The mechanism explains hydrocarbon synthesis in circumstellar clouds.

Abstract

We describe a mechanism that explains the formation of hydrocarbons and hydrocarbyls from hydrogenated graphene/graphite; hard C-C bonds are weakened and broken by the synergistic effect of chemisorbed hydrogen and high temperature vibrations. Total energies, optimized structures, and transition states are obtained from Density Functional Theory simulations. These values have been used to determine the Boltzman probability for a thermal fluctuation to overcome the kinetic barriers, yielding the time scale for an event to occur. This mechanism can be used to rationalize the possible routes for the creation of small hydrocarbons and hydrocarbyls from etched graphene/graphite in stellar regions.